Hi I have a problem with my iMac can you help me

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Level 1

8 points

Hi I have a problem with my iMac can you help me

I have an iMac 2012 which has windows on it. I would like to wipe out the Windows and install macOS instead.

The windows is installed without boot camp, on bare metal.

I have created a flash drive with the installation file for macOS but I am unable to make the computer to boot from the flash drive.

When I open the BIOS by pressing F2 or F8 on restart it loads, however I do not see an option so select a booting device.

When I hold down the Command + R when reinstalling windows loads and I am unable to get to the Apple utilities menu.

Could you please help me make my mac to boot from the flash drive so that I can reinstall macOS.

Thanks!

iMac 21.5″, macOS 10.12

Posted on Aug 3, 2020 11:38 PM

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Answer 1

Best reply

Eau Rouge

Level 8

42,554 points

Aug 9, 2020 11:22 PM in response to dimitar106

Was this installer downloaded/ created before October 2019.

In October 2019 the certificates for several OS's expired, this is probably why you are getting this error.

When you are booted up to the USB you can try resetting the date and time in Terminal (from Utilities in the menubar)

to a date prior to the expiration date. Make sure to switch off your WiFi as this will probably set the date back to today.

Enter a new date, for example or just copy and paste

sudo date -u 011421002015

press Return

enter your password

press Return

Having done that and confirmed the date has changed to the earlier date try installing High Sierra again.

If that does not work then you can download a newly certificated version of High Sierra

from here, Use Safari as your browser, Firefox will not work.

How to upgrade to macOS High Sierra - Apple Support

Go to Section 4 and click on Get macOS High Sierra

this will redirect you to the App Store High Sierra download page,

it should say Get or Download.

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Answer 2

Aug 6, 2020 10:10 AM in response to dimitar106

Hello dimitar106,

We understand you're experiencing an issue when attempting to reinstall macOS, and we'd like to point you in the right direction for a resolution. To get started, we recommend following the guidance outlined here: How to create a bootable installer for macOS

Specifically, follow the steps under "Use the bootable installer". This will allow you to use the drive you've created to access Utilities and reinstall macOS. We hope that this helps!

Take care.

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